They suspect that the travellers are spies - part of the Germans’ Operation Barbarossa. Despite their pleas they are locked up while it is decided what to do with them.

Polly, however, is receiving strange looks from the pilots and clearly unnerving them. When the TARDIS crew discover why this is, it becomes clear that they’re about to get far more involved in the war than they could possibly have imagined.

Anneke Wills was originally going to be the main voice of Tatiana before she expressed doubts about her ability to put on a convincing Russian accent. (BFX: The Night Witches) She does voice Tatiana when the character is impersonating Polly.